1. Field of the Invention
The invention disclosed in this patent relates to an evaporative condenser for cooling and condensing fluids, such as refrigerants in a refrigeration system. The invention incorporates a fogging nozzle for spraying a fine water mist into an evaporative condenser, which will increase the rate of evaporation of cooling water circulating in the condenser, and thus increase the cooling efficiency of the condenser.
2. Description of the Related Art
An evaporative condenser is an integral part of a refrigeration system since it is the device which cools and condenses the refrigerant in the system. The general principles of operation of an evaporative condenser are described, for instance, in Equipment Handbook, Chapter 16 (1983 Edition). The principal components of an evaporative condenser usually include a condensing coil, fan, water reservoir, spray distribution system, water pump, and make-up water supply.
In a typical evporative condenser, the refrigerant is circulated through the condensing coil which is located at the midsection of the condenser. The condensing coil is continually wetted on its outer surfaces by recirculating cooling water pumped from the reservoir at the bottom of the condenser up to the spray distribution system located above the condensing coil. Cooling water from the spray distribution system flows down over the condensing coil. Heat is transferred from the refrigerant, through the wall of the pipes of the condensing coil, and to the cooling water, thereby cooling and condensing the refrigerant flowing through the condensing coil. The spray distribution system provides complete and continuous wetting of the condensing coil to ensure a high rate of heat transfer and to prevent a buildup of residue or scale, which is more likely to occur if the condensing coil is intermittenly or partially wetted.
Cooling water leaving the condensing coil drops down to the reservoir where it is pumped back up through the spray distribution system. Cooling water continuously circulates through an evaporative condenser in this manner, cooling and condensing the refrigerant which continuously flows through the condensing coil.
The fan is located at the lower portion of the condenser, between the condensing coil and reservoir, and takes air from the atmosphere and blows it into the condenser. The air is blown upward through the condensing coil where it causes a portion of the cooling water to evaporate. The cooling water is itself cooled by evaporation, which transfers heat from the cooling water to the air. The air exits to the atmosphere through an air discharge opening at the top of the condenser, and the heat released by evaporation is blown out with the air.
An evaporation condenser therefore transfers heat from the refrigerant to the cooling water, and from the cooling water to the air, discharging the heat to the atmosphere.
Some efforts have been made to increase the efficiency of an evaporative condenser by employing various techniques of heat transfer. For instance, U.S. Pat. No. 3,169,575 states that in the area between the spray distribution system and the top of the condensing coil the cooling water actually absorbs heat from the air. The patent shows cooling water and refrigerant being first pumped through a heat exchanger where some heat from the refrigerant is transferred to the cooling water; cooling water is then directed to the spray distribution system where it is sprayed over the condensing coil. The heat exchanger is intended to adjust the relative temperatures of the cooling water and the air so that, in the area between the spray distribution system and the condensing coil, the cooling water will be cooled by the counterflowing air rather than taking up heat from the air. While the heat exchanger may affect the relative temperature of the cooling water and air above the condensing coil, it otherwise does not affect the rate of evaporation of the cooling water as it passes over and through the condensing coil.
Fogging nozzles have been used on some types of cooling equipment, but not evaporative condensers. For example, U.S. Pat. No. 4,028,906 shows a fogging nozzle for injecting an atomized mist into an air conditioning compressor, but says that it is undesirable to douse the coil with more water than will evaporate, which is what occurs in an evaporative condenser. As another example, U.S. Pat. No. 4,501,121 shows a fogging nozzle in a refrigeration system, but it is used to spray atomized water into the cooling air which circulates within the refrigerated chamber; the nozzle does not spray water into the atmospheric air used to transfer heat from the refrigerant to the atmosphere as in an evaporative condenser.